Q: I sanded a pre-finished birch floor. The previous finish did not come off entirely where the ends of the boards joined as they were ever so slightly offset. To remove the remaining finish in those areas, I used a random orbital palm sander. It looked fine until I applied 2 coats of clear water-based semi-gloss polyurethane. Now that the floor shines, the spots at the ends of boards now look like little dents when light is reflected. I was so disappointed when I noticed this. I very much doubt there is anything I can do to fix this except to sand the entire floor again. I was thinking about using a satin over semi gloss polyurethane for the remaining coats to reduce the sheen. Is it alright to apply satin poly over the semi-gloss?
A: You can apply any sheen over another as long as your fully abrade, scuff, scratch up the previous coat of finish. The problem with pre finished floors is the bevel. These have to be done manually.